Process of extracting rubber.



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UNITED STATES Specification of Letters Patent.

BROOKLYN, NEW YORK.

RUBBER.-

Patented Feb. 5, 1907.

Application filed December 19,1906. Serial No. 348,644.

To (ti/I 11/71/0111 it may concern-.-

Be it known that I, GEORGE B. BRADSHAW, a citizen of the United States of America, re-

siding 1n the borough ofBrooklyn, in the f I I chine which will su ject the pulp to an agitatcounty of Kings and State of New York, have invented certain new and useful ments in the Processes of Extracting Rubber, of which the following is a specification.

My invention relates to a, process for ex- Geog hale, Heeea brasiliensis, rubber bark, chips, &c.

e process consists in the reduction of the rubber-bearing material in the presence of water to its almost individual fibers by asuitable connninuting device, uhich in com minuting cuts rather than rubs or grinds, and in the subjection of this finely-comn'iinuted pulpy material to an agitating and compressing action in the presence of water uhich causes the particles of rubber to ball up, and in the final separation of the bailed-up pellets of rubber from the sludge by gravity.

Marked advantages of the process are that it makes possible the use of continuously-operating machines instead of 'the intern'littent types hitherto used, permits the use of emulsifiers for removing the resin, and furnishes a by-product suitable for making certain grades of paper. 7

In carrying out this process with continuous machines I prefer to use two well-known pieces of machinery. The first is known as the Marshall engine, commonly used in the making of paper-stock and may be of the style as llustrated and described in any of the numerous patents to F. J. Marshall. I prefer to use the Marshall engine because of its eiliciency and rapidity, although the J ordan engine or Hollander may be used or any machine which will comminute woody ma terial in the presence of water without subjecting said material to a rubbing and compressive action, and which will comminute the woody n'iaterial so finely that the pulp formed will tend to settle in water. In other words, it is'csscntial that the first machine reduce the rubber-bearing material in the presence of water by a cutting action, from which rubbing and compression of the material are practically absent, and reduce it so evenly and iinely that it sinks or tends to sink in water: 11'' Ilollanders which are intermittent were used, the beating-roll and bed-plate would have to be so constructed and set that the above effect is obtained.

is, first, reduce the shru The second is the tube-mill, a well-known continuous -process pulverizing-machine 'lhe intermittent type of this machine is commonly called a pebble-mill. Any Inaing and rubbing action can be used; but I prefer a tube-mill because of its continuous operation and automatic feeding and discharging facilities. Heretofore processes of the same purport as mine have not been able to use tube-mills and advantages of this continuous-operating ma- 7 tube-mill to a pulverized state, and, second, ball and agglomerate the rubber. To do this required from two to four hours grinding, and as the different pellets of rubber became freed they would rise to the surface of the water in the mill and gradually become agglomerated into huge balls, which would not discharge from the discharge-pipe, hence nullifying the continuous feature. If the discharge were hastened, so as to allow the rubber to run out before it befectly-extracted shrub would also be dis- Again,'if the tube-mill were opera continuous discharge floating particles of wood riding above the pebbles would tend to ilow right through the mill without being subjected to the action of the pebbles. The intermittent type-mills consequently largely used and the rubberbearing material is ground and extracted in them.

In my rubber is to be extracted can be fed to the 9 tube-mills m an already very finely comminut-ed condition, so that practically all the work required of the tube-mill is the balling up of the rubber into pellets of size large enough to float. As the material fed to the tube-mill is of uniform size and does not require grinding, a tube-mill can be so proportioned that the stream from the discharge end will just equal the feed and the discharged material will have b just long enough in the tube-mill so that all the rubber contained in it will have been balled up into small pellets, but not long enough for the forming of the huge balls referred to above. Also asthe material from my process is so finely comminuted that it tends to sink in water it will Work down in among the pebbles as soon as it process the 'material from which is fed into the tube-mill, thus making complete extraction a certainty.

In the present processes using the pebble mills it has also long been a desideratum to feed iine material to the pebble-mills for the sake of saving time in the pebblemill operation. However, hitherto all efforts to that end have been failures, because it was attempt-- ed to reduce the rubber-bearing material dry. Dry reduction to less than about one-quarter inch size was harmful in at least two ways. In the first place the rubber was oxidized, due to heat generated in the reduction, and, secondly, the rubber was driven full of line splinters of wood, which later in the extraction process became water-soaked and prevented the floating of the balled-up pellets. As generally run at present the pebble-mills are charged to just above the line of the pebbles with macerated, crushed, or cut-up shrub of three-sixteenths to one-half inch size and water, so that the material is like a thick The mill is rotated from one to two sou hoii rs or until the material has been ground so iine that practically all of it except the cork has worked in among the pebbles. Then the mill is iilled nearly full oi water and the rotating continued until the rubber has balled up and floated to the surface of the water. The mill is then discharged into tanks, and the floating rubber and cork is skimmed oil and subjected to further cleaning. The cork at this stage is equal to about liljteen to twenty per cent. of the weight of the rubber. The connninuting in water according to my process overcomes all these dilliculties. The water prevents the heating up of the material and consequent harm to the rubber, and also prevents the filling of the rubber with fine pieces of wood.

The fineness of the connninution and the consequent water-soaked condition of the pill reduce the time required in the pebble,- mill Also the fact that the cork in my process is so iinely cut up that a good deal of it sinks in water results in a product containing very little cork.

Another feature of my process is that it enables the use of dilute caustic alkali or other emulsifier for the purpose of emulsifying, and thus removing a portion of the resins, which commonly occur in nature along with rubber. This alkali may be added to the liquid in which the shrub is comminuted for instance,

to the liquid fed to the Marshall engine-sothat the liquid contains about one-half per cent. alkali. Adding alkali to the liquor in pebble-mills is beneficial; but its effects are slight because the rubber is in such large-sized pellets In my process the resin in the finelycomminuted woodyiiberf and rubber becomes tho oughly subjected to the emulsifying ac-v This use of caustic alkali tions of the caustic. is not essential to-the operation of 'my process, but is only possible when my process 18 used.

The VEST/62' material in my process is the sludge leftin the settling-tanks after the rubber has been skimmed off. It consists of woody material reduced to its almost individual fibers and withoutfurther' treatment is in exactly the right condition for use as pulp in making paper.

In using myprocess with the machines for which preference has been expressed above I proceed as follows: The rubber-bearing material is fed along with water or wat containing caustic alkali to the Marshall engine. The fed material should be of about three-sights inch size and may have been re duced to this size by any convenient process. Some material will need previous soaking for best results. The amount of water required will yary with the material used. For Guayhule I use from one to two barrels of water to each barrel of shrub. From the Marshall engine issues a continuous stream. of pulp, which is run directly into the feed end of a tube-mill. The tube-mill needed for taking the discharge of a standard Marshall engine is about twenty-two feet long by live feet in diameter. I prefer the Abbe spiral feed and discharge mill equipped for wet grinding for this purpose. The material reuires about fifteen to thirty minutes to work tirough this mill when fed as fast as the Marshall engine will deliver it. The dis charge from the tube-mill consists of a sludge containing woody matter which sinks in water and small pellets of rubber which float. This discharge is led into tanks from which the floating pellets of rubber are skimmed.

I claim as my invention- 1. The continuous process of extracting rubber from rubber-bearing plants or portions. of plants which consists, first, in reducing the nzaterial in the presence of water by a cutting'action to its almost individual fibers, and at the same time comninuting the rubber so that the resulting pulp of rubber and fiber will sink or tend to sink in water, second, in separating this pulpinto a floating and sinking portion by any suitable means, third, in collecting the floating portion con taining the rubber, and in further cleansing this portion to obtain clean rubber.

2. The process of extracting rubber from rubber-bearing plants or materials which consists in reducing such material to practically its individual fibers by cutting action in the presence of an emulsifying liquid, subjecting the pulp thusfornied to rubbing and agitation in the presence of anexcess antount of liquid until the rubber portion of the pulp has become agglomerated into such sized particles that it will float in water, collecting the mixture in suitable receptacles, where, if necessary, the specific gravity of the liquid is modified by suitable neans to permit gravitational peparation, allowing gravity to act ICC and skimming off the resulting floating rubher.

3. The process of extracting rubber from rubber-bearing plants or materials which separation, allowing gravity to act and 5 consists in reducim such material to practiskinnringofl the resulting floating rubber. callyi s individual nbers by cutting action in i In testimony whereof I have signed my the presence of a liquid, subjecting the pulp name to this specification in the presence of in suitable receptacles Where, if necessary, the specific gravity of the liquid is modified thus forn ed to rubbing and agitation in the two subscribing Witnesses.

presence of an excess anount of liquid until GEORGE B. BRADSHAW. I the rubber portion of the pulp has become Witnesses:

agglomerated into such sized particles that WILLIAM ABBE,

it will float in water, collecting the mixture WALTER ABBE.

by suitable 11163118 to pernut gravitational 15 

